Whose glasses are these?
They're Mark's glasses.
Whose ball is this?
It's Mark's ball.
Whose dress is this?
It's Susan's dress.
Whose books are these?
They're Mark's books.
Whose dog is this?
It's Susan's dog.
Whose apple is this?
It's Susan's apple.
Whose cap is this?
It's Mark's cap.
Whose doll is this?
It's Susan's doll.
Whose cat is this?
It's Mark's cat.
Whose crayons are these?
They're Mark's crayons.
Whose rulers are these?
They're Susan's rulers.